Controlled slippage actuation systems use a power source whose power is distributed to one or multiple mechanical outputs through MR fluid clutch apparatuses. These actuation systems are alternatives to commonly used electric actuation systems, when high load and high dynamic performance are sought. They show similar dynamic performance and may represent an overall weight reduction.
Other state-of-the-art distributed power devices rely on hydraulics or electromagnetic actuation. Hydraulic actuation is highly reliable in avoiding mechanical jams, but has a fundamentally limited dynamic response and efficiency. Furthermore, implementation of hydraulic systems into commercial applications is often problematic as hydraulics are prone to leakage and lead to increase maintenance costs. Electromagnetic actuation offers an alternative to hydraulic actuation. For example, actuation systems using direct-drive electric motors show similar dynamic performance but may be heavier in comparison to controlled slippage actuation systems, whereas actuation systems using geared electric motors may have lower dynamic performance than controlled slippage actuation systems, due to the gearing. Indeed, when coupled to reduction gearboxes, electromechanical actuators are much lighter and less expensive than direct drive solutions, but their high output inertia, friction and backlash greatly diminish their dynamic performance.